A320 North of Woking Improvements, Surrey – UK

The A320 North of Woking Improvements is a major highway scheme designed to increase capacity, improve traffic flow and support future housing development across Runnymede. As part of the works,…

Sector / Application

Infrastructure, Slope Stabilisation & Embankments

Overview

The A320 North of Woking Improvements is a major highway scheme designed to increase capacity, improve traffic flow and support future housing development across Runnymede. As part of the works, the existing road required widening between Ottershaw Roundabout and M25 Junction 11.

Excavation into the toe of an existing wooded embankment created a new cutting approximately 690m long and up to 2.5m high. The predominantly granular ground conditions, combined with slope gradients of up to 34°, required a long-term solution to stabilise the cutting and secure approximately 2,000m2²of erosion control facing.

The design also needed to accommodate variations in slope height and gradient across the site, while allowing installation to be completed efficiently alongside the live highway.

Solution

Platipus supplied an Anchored Reinforced Grid Solution (ARGS) to stabilise the cutting and secure the reinforced erosion-control geotextile. The solution primarily utilised anchors with a 120-year design life, while a localised section outside the highway specification utilised anchors with a 60-year design life.Across the shallower section, 1m-long Stealth Anchors retained the geotextile against the slope. Along the steeper sections, 3.5m-long Stealth Anchors were installed in up to four rows, providing additional support to the cut face.The anchor arrangement was adapted to suit variations in the slope geometry throughout the site. Each anchor was driven to the required depth, loadlocked and tensioned before a 150mm load plate was fitted to secure the geotextile against the slope surface. The resulting system provides long-term slope stability and effective surface erosion protection.